Heating apparatus



C. A. DUNHAM El' AL HEATING APPARATUS Filed July 7, I 1930 i v012 -z" and-Adra June 18, 1935.

June 18,-1935- y c. A. DUNHAM ETAL A 2,005,224

. HEATING APPARATUS Fild July 7, 1930 5 sheets-smet 2 .Julie 18, 1935- c. A. DUNHAM E'r AL t 2,005,224

HEATING APPARATUS Filed Jury '7, 1930 5 sheets-sheet 5 Mal 14j y dAUZranam June 18, 1935. c. A. DUNHAM `ET Al. 2,005,224 yHEATING APPARATUS Filed Jul'y '7, 1930 5 sheets-sheet 4 June C. A. DUNHAM AL HEATING APPARATUS Filed July 7, 195:50

5 Sheets-Sheet 5 .iQ/'Wwf ggg;

C www 'Patented June 18, 1935 Clayton A. Dunham 'and Aubra R. Dunham,

Glencoe, Ill., assignors to Experimental Laboratories Incorporated, Chicago, Ill., a corporation oi' Illinois Application July 7, 1930, Serial No. 466,002

sclaims.

This invention relates to a new and improved heating system of the internal combustion boiler type in which a heating medium consisting of mixed steam and products of combustion is '5 created and transmitted to and through the radiators.

According to this invention the entire system is operated under a reduced pressure produced by a fan or other suction means connected with the outlets of the radiators. This exhausting mechanism draws out from the radiating system and expels to the outer'atmosphere the noncondensible gases after they have given up most of their heat in the radiators, and also maintains a sub-atmospheric pressure in both the radiating system and the generator. Steam condensed in the radiating system is returned by gravity to the generator for reconversion into steam. The sub-atmospheric pressure maintained in the generator yserves to draw in air from the outer atmosphere for combustion purposes, this sub-atmospheric pressure being reduced to provide for an increased supply of combustion air, when the number of radiators in service and hence the volume of the condensing space and the corresponding rate of condensation is increased. The entire system within the building to be heated is closed, and since the system is operated under reduced pressure, if any leakage does occur, it will becf air into the system rather than the escape of steam or combustion gases therefrom. Means manually operable from a location in the building remote from the generator is provided for starting and adjusting the generator burners, and for starting and stopping the exhausting mechanism. Signal devices'adjacent the manually operable control means indicate the condition at any time of the generator and exhausting apparatus. Thermostatic control means -automatlcally adjusts the res in the generator in accordance with temperature requirements.

The principal objectl of this invention is to provide an improved heating system oi.' the type brieiiy described hereinabove and disclosed more in detail in the speciilcations which follow.

Another object is to provide a simpliiied heating apparatus of the internal combustion boiler type operating under sub-atmospheric pressures.

Another object is to provide an apparatus oi.'

this type designed to prevent leakage oi!` gases` into the building. i

Another object is to provide improved remote control means for stopping, starting and adjusting the various features of the apparatus.

Another object is to provide improved signal means for indicating the condition oi.' the operating parts.

Another object is to provide improved thermostatically controlled means for adjusting the generator ilres in accordance with temperature 5 changes at a remote location.

Another object is to provide an improved type of generator for a mixed iluid heating medium.

Another object is to. provide a simple, inexpensive 'and eilicient heating system for small 10 structures, which will give a maximum of convenience and comfort at aminimum of care and expense.

Other objects and advantages of this system will be more apparent from the following detailed 15 description of one approved form of apparatus adapted for carrying out theprinciples of this invention.

In the accompanying drawingsz' Fig. 1 is a general diagrammatic the heating system.

Fig. 2 is a central vertical section through the generator.

Fig. 3 is a plan view of in horizontal section. f

Fig. 4 is a detail plan view, partially in section, showing the ignition apparatus and pilot burners.

Fig. 5 is an elevation, partially in Vertical section, through one of the thermostatic control devices.

Fig. 6 is a vertical section, taken substantially on the line 6-6 of Fig. 7, showing the electrically operated valve and switch mechanism.

Fig. '1 is a vertical section, taken substantially on the line 1-1 of Fig. 6. 35

Fig. 8 is a detail vertical section, taken substantially on the line 8-8 of Fig. '7.

Fig. 9 is a diagrammatic assembly showing a wiring diagram and the fuel-feed connections, and a vertical section through the temperature 40 controlled valve.

Fig. 10 `is a partial elevation and partial vertical section showing one of the radiator inlet valves. l

The main elements of the apparatus are a gen- 45 erator A for the heating medium, a burner control mechanism indicated generally at B, a manually operated remote control and signal mechanism indicated. atC, a thermostatically operated temperature control mechanism indicated at 50 D or D', a'radiating system comprising the several radiators E, and an exhausting mechanism indicated at F. The generator A may take a variety of forms, a preferred form o! generator being disclosed by of adjustment elevation of 20 the generator, partially way of example in the present application. The generator herein disclosed is claimed in our copending application Serial No. 759,966, filed Deceber 31, 1934.

One of the essential characteristics of this generator is that it is entirely closed except for the inlets for water, fuel and combustion air, and the outlet for the heating medium and excess water, none of these having any direct communication with the atmosphere within the building so that areduced pressure may be maintained within the generator and the escape of fluids therefrom is prevented. The generator may be made of metal or suitable refractory materials, or both, preferably comprising an outer metallic shell covered with suitable insulating material (not here shown) in order to prevent heat losses. In the example here shown, a lower substantially closed metallic housing I rests upon and is sealed to a concrete supporting base 2 formed with the sump 3, from which leads drain pipe 4 provided with the downwardly looped water seal 5. Drain pipe 4 may empty into the sewer connection :indicated at 6. A side extension 'I of the lower casing I houses the burner and control valve mechanism, and a conduit 8 for the combustion air leadsin at 9 from the outer air and connects with the housing extension 1, from which this air flows through and around the burner |1 into the main housing I and thence with the fuel into the combustion chamber. If permitted by local ordinances, the air inlet 8 may take in air from within the building without substantially affecting the operation as hereinafter set forth. Suitably mounted in and supported by the metallic cover plate I0 of lower casing I is the main lower combustion chamber formed of suitable refractory material. The refractory shell I! for the combustion chamber may be supported in a metallic casing I2 formed with a lower inwardly extending supporting flange I3 and supported from cover plate by the angle brackets I4. The central cylindrical combustion chamber I5 is open at its upper end and provided adjacentits lower end with a tangential inlet opening I6, through which the fuel and flame from main burner I1, and the combustion air, enter the combustion chamber |5. Due to this tangential opening, the combustion fluids and flame take a spiral or spinning path through the combustion chamber I5, whereby a very long flame and complete combustion may be attained almost entirely within the relatively small combustion chamber before the hot products of combustion pass out into the mixing chamber thereabove.

'Ihe outer substantially cylindrical metallic shell I8 of the steam generator and mixing charnber is supported by and secured to the cover plate I0 of lower casing I by means of annular bracket |9. The dome or -cover 20 of casing 8 leads up to a central opening, with which communicates the outlet or main supply pipe 2 I, through which the heating medium is conducted to the radiating system. An inner metallic shell 22 is provided at its lower end with an outwardly extending flange 23 which joins with the outer shell I8, and is formed at its top with a dome 24 provided with a central opening through the downwardly extending cylindrical overflow flange 25. This overflow opening 26 is in line with the outlet pipe 2| and also serves as an outlet for' the heating medium from the mixing chamber 21 within inner casing 22. A shallow flash plate or pan Y28 is supported by legs 29 from cover plate I0, the flash plate 28 being positioned substantially centrally within the mixing chamber 21. A water-heating pan 30 is supported beneath overflow opening 26 by post 3| extending upwardly from the flash plate 28.

A water supply pipe 32 communicates with the annular water space 33 between casings I8 and 22. This pipe 32 leads from the lower portion of return pipe 34 through which condensate is returned to the generator. A supply pipe 35 leading from the outside water supply and provided with cut-off valve 36 also communicates with the water inlet pipe 32. A scale-collecting pocket 31 may be provided at the lower end of the water return pipe 34.

The space between cylindrical casings |8 and 22 will be filled with water up to the level of the upper edge of overflow opening 26. 38 is a drain plug whereby this annular chamber 33 may be drained and flushed out, and 39 is a pet-cock to test the upper water level. As additional water slowly accumulates in this annular space 33, due to the return of condensate from the heating system, the water will overflow through opening 26 into the heating pan 30, as indicated by the falling drops 40. Excess water in heating pan 30 will overflow, as indicated by the drops 4| onto the flash plate 28. The water which lls the annular space 33 and the pan 30 when the operation of the generator is flrst started will expand when heated so as to start the overflow into pan 30 and onto flash plate 28.

In operation, the highly heated products of combustion rising from vcombustion chamber I5 pass under and around the flash plate 28 so as to convert all or the greater portion of the film of water thereon into steam. These products of combustion also contact with the water falling through or from overflow opening 26 and from heating pan 3U, whereby additional steam is generated. The rising products of combustion highly heat the pan 30 and the water contained therein so that some steam will be generated from this body of water and the Water which drops onto the flash pan 28 will already be raised to a high temperature. The hot gases rising through mixing chamber 21 will soon heat the annular body of water in chamber 33 so that additional steam is generated from this water, all of the mixed gases consisting of steam and products of combustion passing out through the main supply pipe 2| to the radiating system. It will be noted that the mixing chamber 21 is entirely closed at its lower end by plate I0, the only inlet being through the relatively small inlet opening I6 provided for the flame and combustion air, and the only outlet being through the supply main 2| for conducting out the heating medium. The entire generator will be protected by an outer covering of insulating material (not here shown), so that the heat losses will be minimized, and practically all of the heat generated is carried out to the radiating system by the heating medium discharged through pipe 2|.

Since practically al1 of the condensate from the radiating system is returned to the generator through pipe 32, and since additional water is always being formed in the combustion process from the hydrogen in the gas and oxygen in the air, there will ordinarily be a surplus of water supplied to the generator. Any excess water that is not vaporized on flash pan 28 will overflow, as indicated at 42, onto the'plate I8 forming the bottom of the mixing chamber 21, and then drain out through pipe 43, water seal 5, and drain pipe 4 to the sewer connection 5. The water seal 5 prevents the inow of air at atmospheric pressure through pipe 55', or the escape of combustion gases through pipe 55 from the mixing chamber.`

The heating medium passes from supply main 2l through the respective risers 55 and inlet valves 55 into the several radiators E. While only three radiators have here been shown by way of example, it is to be understood that a greater number' of radiators could be used. Each inlet valve 55 comprises the usual cut-oi! valve operated by handle 55, and a metering plate 51 provided with a central oriiice 55 is interposed between the valve chamber and the passage 59 leading into the radiator E. The orifice 55 in plate 51 will be proportioned to meter the rightl proportion'of heating medium to each radiator, depending upon the size, volume and condensing capacity of the radiator. It "will be understood that when valve 55 is closed pratically no heating medium at all is admitted to the radiator, but when the valve is opened, a restricted flow of heating medium is admitted to the radiator through the orice plate 51.

Discharge pipes 55 lead from the respective radiators E into the vertical return main 55, in

the lower portion of which the condensate from the radiators accumulates and flows back through pipe 52 into the'generator. At a point somewhat above the water level in the generator A, a branch pipe 5I leads from return main 55 to the exhausting apparatus F. This exhausting apparatus comprises a suitable fan or other suction device 52, driven by electric motor 55 and adapted to draw gases from return main 55 through pipe 5I and discharge these gases through pipe 55 into the outlet flue or chimney, indicated in dotted lines at 55'.v .This exhausting apparatus F, not only draws out and expels the non-condensible gases from the/ radiating system'but serves to createa small suction or sub-atmospheric pressure in the system which is increased by the vacuum created by condensation of steam in the radiators E. This sub-atmospheric pressure, which extends into the generator A, serves to draw in the combustion air at atm heric pressure and also prevents leakage of combustion gases from any part of the system since leakage (if'any occurs) will be of air into the system, due to the sub-atmospheric pressure existing therein.

'I'he manually operated control mechanism B and C, whereby the heat is turned on and oif from a point remote from the generating apparatus,

yfor example from some room in the house that is being heated, will now be described, referring more particularly to Figs. 6, 7 and 8, and the diagrammatic showing in Fig. 9.- The fuel gas flows into the valve casing 55 through pipe 55 from 4the source of supply, such as the city gas mains.

The cylindrical hollow sleeve valve 51 is rotatably journaled i'n valve casing 55, this sleeve valve being. closed at one end'55, and'open at the other end- 59, to communicate through pipe unin 55 with the thermostatically controlled regulating,

valve5l. Sleeve valve 51 is formed with an invlet port ,52 which, in one position of the valve,

communicates with a similarly shaped .port 55'in the valve casing communicating. with the main supply chamber 55. An arcuate extension 55 of supply chamber 55 extends around one side of the rotatable sleeve valve, and a smaller inle port 55 leading from extension 55 isadapted to communicate with the inlet port 52 in the sleeve valve when this valve has been rotated through an arc of 90 degrees from the position` shown in rig. s. The sleeve valve s1 is adapted to bev rotated in one ldirection through successive arcuate steps of 90 degrees each, by means hereinafter disclosed. In one position, as shown in Figs. 7 and 8,

the ports 52 and 55 will be in communication and a maximum flow of fuel gas through the valve will be permitted. At the next following position of the valve, the ports 52 and 55 will be in communication and a restricted flow of gas through the valve is permitted. This restricted flow may be regulated by means of the adjusting screw 51, which is adapted to vary the effective size of port 55. In the next two successive positions of sleeve valve 51, reached by arcuate steps of 90 degrees each, the flow of gas through the valve will be entirely cut off.

From the closed end 55 of sleeve valve 51, a cylindrical metallic shaft or spindle 55 projects face with a removable closure plate 15. A disc 1I, the hub of which is secured to spindle 55 by any suitable means, such as pin 12, is provided on one face with four similar pins 15 spaced at equi-distant points around theperiphery of the disc. A lever .15 fulcrumed intermediately at 15 i into the contact box 59 provided on its opposite has its lower arm 15 pivotally connected with the outer end of the core or ,armature 11 of a solenoid or electro-magnet 15, Apawl 15 having one hooked end 55 adapted to engage any one of the several pins 15, is plvotally mounted at its 'other end `5| on the free upper end of arm 52 of intermediately pivoted lever 15. A coiled contractile spring 55 is anchored at one end 55 in housing 55, and is secured at its other end to a lug 55 projecting upwardly from pawl 19 near its pivoted end 5i. This spring 53`tends to return the parts to the lposition shown in Fig. 6 when magnet 15 is de-energized, and also tends to swing thehooked end of pawl 19 downwardly so as to rent flows from transformer 55 through wires 55,'

95 and 9| to the normally open push button 52 of the manual control mechanism C (see Fig. l) then vthrough wire 93 to the electro-magnet 15 and wire 95 back to the transformer. Whenever push button 92- is closed, the magnet or solenoid 15 will be energized, thus drawing in core 11 and through lever 15 moving Apawl 19 toward the right (Fig. 6), therebyy -turning the rotary assembly consisting of sleeve valve 51 and spindle 55 and the parts mounted thereon, through an angle of 90 degrees. When the push button 92 is released, th'e magnet 15 will be de-energized and spring 55 will return the parts`to the position shown in Fig.V 6, the beveled end '55 of pawl 19 sliding up over the next succeeding pin 15 until the hooked end 55 of the pawl can bemoveddown into engagement with ,this pin through the eiort of spring 55 exerted on lug 55 of the pivoted pawl. The next time push button 92 is closed, the same cycle of events will be repeated and the rotary assemblywill be shifted in the same direction through vanother arc of degrees.

A pair of signaljvlights. which may conveniently comprise a lower red light and an upper white light 91, lare preferably mounted adjacent, the push button 92 as apart of the control mechanism C, as indicated in Fig. l. A contact bar 95 is constantly in lengagement with spindle. 55, this contact 98 being connected through wire v99 with one terminal of transformer 88. A pair of contact pins and |0| mounted in spindle 68 and spaced 180 degrees apart are adapted to alternatively contact with the spring contact member |02, which is connected through wire |03 with one terminal of light 91. A similar pair of contact pins |04 and |05, spaced 90 degrees apart, are adapted to contact with spring contact member |06 which is connected through wire I 01 with one terminal of the red signal light 96. 'Ihe other terminals of the signal lights 96 and 91 are connected bythe respective branch wires |08 and |09 with the wire 89 leading back to transformer 88.

A coiled leaf spring I |0 is anchored at its inner end I I I in the housing 69, and carries at itsouter end a penduluml I|2.'A normally open contact member I|3 is mounted at an intermediate point on the coiled spring 0, said contact I|3 being adapted to intermittently engage with a relatively fixed contact member I I4 carried by arm I I5 as the spring vibrates, due to the oscillatory movement of pendulum II2. A finger I I6 is anchored on the spindle 68 in such a position that when the rotary assembly is moved through one arcuate step of 90 degrees, this finger ||6 will snap past the pendulum ||2, thus throwing this pendulum into oscillation and intermittently making and breaking the contacts II3, |I4. The primary winding of a spark coil I|1 is energized from transformer 88 through a circuit comprising wire 89, wire II8, spring ||0, Contact II3, contact II4, wire I I9, primary of coil |I1 and wire |20 back t0 transformer 88. The spark-plug |22 is connected in series with the secondary of spark coil II1 through wires I2| and I2 I It will now be apparent that whenever the pendulum I I2 is set in motion, the contacts II 3, ||4 will be intermittently brought into engagement so as to give a series of sparks at the spark plug I 22.

A disc 23 of insulating material is fixedly mounted on spindle 68, this disc having one fiat side |24. 'A movable contact member |25 willbe.

held in engagement with a relatively xed contact member 26 as long as the spring arm |21 which carries the contact |25 is held up by the cylindrical periphery |28 of insulating disc |23, on which it rests. Whenever the at face |24 of the disc comes under the arm |21, this spring arm will' be, permitted to move downwardly, thereby breaking the circuit by disengaging the contacts |25 and |26. One of these contacts |25 is connected with main 81 through wire |29. The other contact |26 is connected through wire |30 with one terminal of the exhauster motor 53. The other terminal of this motor is connected through wire |3| with the main 86. It will now be apparent `that as long as the contacts |25 and |26 are held together, the exhauster motor 53 will operate, but when the contacts |25 and |26 are separated, the motor 53 will be de-energized and the exhauster fan will stop.

The rotary assembly comprising sleeve valve 51 and spindle 68 and the contacts carried thereby, rotates intermittently in a. clockwise direction,

" as seen in Figs. 6 and 8. In the first or olf position, with all parts at rest or not functioning, this rotary assembly will be turned back in a counter-clockwise direction 90 degrees from the position shown in Figs.- 6 and 8. At this time the valve 51 will be closed and no gas will flow to the burners since closed portions of the sleeve upper white light `At this time the spring arm |21 Will be resting on the fiat side |24 of insulating disc I 23 and contacts |25 and |26 will be separated so that exhauster motor 53 is de-energized. At this time none of the contact fingers |00, |0|, |04 or |05 will be in engagement withi'the spring contacts |02 and |06 and neither of the signal lights 96 or 91 will be energized. The finger |I6 will be back 90 degrees in a counterclockwise direction from the position shown in Fig. 6, thus being behind the pendulum ||2 and in position to impart an oscillatory movement to this pendulum when swung to the Fig. 6 position.

With the parts in the positions just described, if push button 92 is closed, the solenoid 18 will be energized acting through the lever and pawl mechanism already described to swing the rotary assembly through an arc of 90 degrees to the positions shown in Figs. 6, 7 and 8. The valve will be moved to the fully open position shown in Fig. 8 so as to supply a maximum flow of gas to the burners. The finger ||6 will snap past the pendulum I I2, thereby causing the spark plug |22 to give ai series of sparks and'ignite the pilot lights, hereinafter described. The cylindrical surface |28 of disc |23 will be moved under spring arm |21, thereby closing the contacts |25, |26 and causing the exhausting mechanism F to operate. The two contact fingers |00 and |04 will be moved into engagement with the spring contact arms |02, |06, thereby causing both signal lamps 96 and 91 to be lighted. The two lights 96 and 91 burning simultaneously indicate that the main burner I 1 is being supplied with a maximum iiow of gas.

If it is desired to restrict the iiow of gas to the burner I1 and thus cut down the heat output, contact button 92 will be closed a second time, thereby moving' the rotary parts through a second arc of 90 degrees. This will bring the port 62 in sleeve valve 51 in line with the restricted inlet port 66, whereby only a reduced iiow of "gas to the burner is permitted. The contact fingers |00 and |04 will be moved out of engagement with spring contacts. |02 and |06, but the contact finger I will be moved into engagement with spring contact |06 so as to continue the illumination of the lower red light 96, thus indicating that the low or reduced heat is on. The 91 will not be illuminated at this time. 'I'he exhauster will continue to function since the cylindrical surface- |28 of disc |23 is still in contact with spring arm |21.

Ay third operation of push button 92 will completely close the valve so as to cut off all iiow of gas to the burners (both main and pilot burners). However, the exhauster will continue in operation since the cylindrical surface |28 of disc |23 is still beneath the spring arm |21. Even though the fires have been shut off, the exhauster will continue to draw the unused heating medium already generated into the radiators where the heat will be given off where needed, instead of being wasted in the generator. At this time the contact pin |0| will be moved into engagement with spring contact |02 so as to illuminate the white light 91, the red light 96 being de-energized since both contact pins |04 and |05 will be out of engagement with spring arm |06. A fourth operation of the push button 92 will complete the cycle and return all of the parts to the position rst described, with both lights out, the valve completely closed and the spring arm I 21 resting on l 3,0055224 lat side |24 of disc |23, so thatthe exhauster. I

fan will cease to operate. x

The gas flows from valve casing 55 through I union 60 into the valve casing 6|, already. re-

ferred to, which contains a web |32 separating the inlet chamber |33 from the outlet chamber |34. When the passage |35 in web |32 is open, the gas will flow from chamber |33 into chamber |34 and thence through pipe connection |36 to the main burner I1. A small pipe |31 leads from the inlet valvechamber |33 to the nozzle |38 of vthe pilot burners which nozzle, is positioned, in

'the upper end of a. chimney |39. A relatively small pilot flame |40 projects through the open upper end of chimney. |39 and is adapted to be ignited by the spark plug |22, already. described. This ame |40 in turn ignites a larger pilot dame |4| which projects throughv an opening |42 in the side of the chimney into position to ignite the main burner |1. It will be noted that these pilot lights will burn at any time that gas is allowed to flow through the electrically operated valve 55 into the temperature control valve 6|.

A small gas pipe |42 is-connect'ed by fitting |43 into the inletchamber |33 of valve 6|, the pipe |42 extending into the closed chamber |44 of thermostatic temperature control device D, a pipe |45 leadingfrom this chamber |44 to a pilot burner |46 positioned in the lower end of chimney |39, already referred to. The pipe |45 extends into chamber |44 and terminates in an open flared end |41 adjacent a ilexible diaphragm |48 which forms one* wall of chamber |44. A plunger |49 is adapted to depress the diaphragm |48 and thus close the' opening ...L41 to discharge pipe |45, the plunger being operated by a thermostatic bar |50 which may be set to operate at certain designated temperatures by means of the adjusting device indicated at |5|. Normally, Whenever a flow of gas is permitted-to pass to control valve 6| through the electrically operated valve 55, vgas will ow through pipe |42 to chamber |44 and thence through outlet pipe |45 to the pilot burner |46. The gas from .this burner will4 ow up the chimney |39 and be ignited by the previously ignited pilot flames |40 and |4| at the upper end of i'fhechirnney, this pilot burner |46 then flashing down to the normal position indicated in Fig. 9. Pilot |46 will burn continuously until a predetermined temperature is reached at the location of thermostatic control device D, whereupon the diaphragm |48 will be depressed to'close the outlet |41., thus cutting off the supply of gas to pilot burner |46. lA thermostatic bar' |52 is positioned in chimneyA |39 above the pilot burner |46, and when heated byy this burner, this bar |52 will bend toward the left, Fig. 9, and operate through rod '|53 to push over to the left the lever |54, which is connected through rod4 |55 with the main valve |56 for closing port- |35 in web |32. A' springl |51 serves to snap the valve to its fully open position when lever |54 has been moved past a mid-point. Valve |56 is mounted iir universal adjustment on a ball |58 at the end f operating rod |55, and spring |59 serves to seat the valve over port |35. A

Before operations are commenced, thermostatic bar |52 will be cold and main valve |56 willbe closed, the parts being in the position shown in Fig. 9.' As soon as the electrically .operated valve 55 is opened and gas ilowsto chamber |33, gas will immediately flow from this chamber to the several pilot burners already described, the pilot flame |40 being ignited from spark plug |22 and subsequently serving to light the main pilot iiame |4I and the control pilot flame |46, in the manners already described. 'Ihe ilame |46 will heatup bar |52, which will move to the left, causing main valve |56 to beopened, thus permitting gas to flow to the main burner |1 the flame of which will be ignited from the main pilot flame |4|. All of these burners Will continue to operate until the maximum temperature for which adjusting means |5| is set is -reached at the location of control .device D or D', whereupon this ,device will operate to c ut oi the flow of gas through pipe |45 tothe pilot burner |46. lThe thermostatic bar |52 will now cool olf and move toward the right, whereupon the main valve |56 will be closed to cut ol flow of gas to main burner |1. The pilot llames |40 and |4| will continue to burn. When the temperature adjacent control device D has fallen suiiiciently, the diaphragm 48 will move awayfrom opening |41, thus permitting gas to again flow to the pilot burner |46, the ilamel of which will again be ignited from the pilot llames |40 and |4|, again heating bar |52 so that main valve |56 will be opened and main burner |1 will again be ignited from the pilot llame 14|. This ycycle of operations will repeat itself as temperature conditions demand. If the temperature should'fo'rany reason rise too high, the main burner |1 will1 be cut off in the manner already described, until the temperature has been lowered below the desired maximum. In actual operation, the main valve |56 will stabilize itself in an almost fully'open position, such that theheat delivered from burner |46 is just sufficient to keep the various elements of the 'valve system. in equilibrium. l

In'l the example show'n in Fig. 9, the temperature control device DA has beenpositioned in -or adjacent the outlet port 5| for the exhaust gases, so that when these gases come out too hot, thus 'indicatingthat'more heat is being furnished to the-radiating system than is demandedthereby, this device D will operate to cut ol the burners. The control Vdevice D' (which may be connected in series in pipe line |42 with the similar device D) could be positioned in any room of the building thatis to be heated, and adjusted to be reture is exceeded at the location of any one of these devices D or D', the supply of gas to pilot |46 `will be cutoff. l

To summarize the'operation, after a period of disuse and" assuming that the generator is properly suppliedv with water, it is merely',` necessary for theoccupant of the'building togpress the co1'1-trol`buttoriu92 in order tostart the system. Gas vwill immediatelyabe'f supplied 'tothe pilot burners and 'they will bejautomatically ignited, and the main burner, `|1`wi1lbe putpi'nto operation after mai'nvvalve v|56Nhas been opened by the operation ofjpilot burner. |46. The exhauster. will be put into Voperation so 'asftolower the pressure inthet system, drawing combU-tioh air into the generatorand causing the ing kmedium to flow in tofthe radiating"syw l@ coded. non-cuidensiblev gases' wmf from the building'throughl outlet 'pip y iiue 54', and the'jcondensate and watergwnerated by the combustion process will bereturned to the generator. 'I'hejautomatic temperaturefcontrol vdevices D or Djwill ,function to'cut "downjor turn oi the main burner when desire'dmaximum temperature has been reached either in the gases that are being withdrawn from the system, or in such of the spaces being heated as have their temperatures controlled by the thermostats D positioned in these spaces. In mild weather when less heat is demanded from the system, the control button 92 can be pressed a second time so as to manually cut down the maximum flow of gas to the system. By pressing the control button 92 a third time the functioning of the generator may be entirely discontinued by cutting off all of the burners, but the exhauster will continue to operate so as to keep up a flow of the generated heating medium through the radiating system, thus keeping the radiators warm as long as any of this heating medium remains. A fourth operation of button 92 serves to cut off the exhauster and entirely stop the operation of the system. It will be noted that when the exhauster is out of operation there is no flow of gas to any of the burners, including all pilot burners, so there is no danger of unburned gas or products of combustion escaping into the building. At all times when the burners, or any of them are in operation, the exhauster is operating to reduce the pressure in the system so that if any leakage occurs it will be of air into the system rather than of gases out of the system into the building.

By having one or more of the inlet valves 45 drilled so that they can never be fully closed (at locations where heat will usually be required, if at all), a diminished iiow of fluid through such radiator or radiators will be permitted even though all of the inlet valves 45 are closed. Since such radiator or radiators will probably be unable to utilize all of the heat developed, the hot gases will be drawn out through pipe causing control device D to operate to shut oi the main burner in the manner already described.

It will be noted that all of the main valves, burners, and operating parts therefor are carried by the removable door plate I 60 forming one wall of casing extension 1, whereby all of these parts will be readily accessible for testing, replacing, repairing, etc.

Emergency pressure relief valves and observation ports may be installed in each of the supply and return sides of the system. In Fig. 2 the casing |6| has a lower flange |62 for holding to the top 20 of the generator, and is internally threaded in its upper end |63 to receive the supply main 2|. The casing |6| is formed internally so that water will 4drip and run downward out of the casing. The ap or closure |64 is hinged at its upper edge |65 and rests upon the inclined seat |66 so that it will be held shut by gravity, also by the outer atmospheric pressure when the system is normally operating under a partial vacuum. The flap |64 is thick enough not to warp under the temperatures to which it ls subjected, and may if desired, be made of brass or other non-corrosive metal to prevent rusting shut. If, for any reason, super-atmospheric pressures should be developed in the system, this fiap valve will blow open and relieve the pressure. The flap |64 may also be raised manually for observation purposes.

A slmilar :flap-valve |61 is positioned in the return main, for example, above the connection with pipe 5|, as shown in Fig. 1. This relief and observation valve |61 is the same as the valve |6|, except that an interiorly threaded pipe-receiving lower end similar to the upper end |63, is substituted for the attaching flange |62.

These heating units are designed for heating small or medium sized homes, but in case of a larger structure where one of these units is insufcient, two or more units may be combined for simultaneous operation. A removable end plate |68 is provided at the outer end of housing extension 1, whereby two of these housings may be connected together and both supplied with air from a single inlet pipe 8.y The return main 34 may be provided with two branch pipes 32, whereby condensate will be distributed between two generators A, and a single exhausting mechanism F can withdraw and expel the gases from both systems if desired. The same control devices, both manual and automatic may be connected up to simultaneously control both generators, or the control devices may be kept separate, if separate Zone control is desired. It will be obvious that this same principle can be applied to more than two units. In case two or more generating units are thus used, a larger exhausting fan F may be required, if only one is used.

It will be noted that these heating units are entirely self-contained and have no fluid outlet or inlet connections to permit escape of gas into any portion of the building being heated, and practically all portions of the generator and piping can be completely covered or insulated so as to reduce heat losses to a minimum. Practically the only heat losses will be in the gases expelled through the exhauster into the flue 54, and ordinarily these gases will give up most of their heat before being withdrawn from the radiators E. In case these discharge gases become too hot, the thermostatic device D will function to cut down the supply of heat to the generator.

The inside of all metal parts, such as the generator and the piping, that are subject to the corrosive action of the combustion gases may be provided with a vitreous coating or other form of rust proofing. This corrosive action is largely caused by excess air in the system. Since this improved system operates under a vacuum, excess air is practically eliminated and corrosion is minimized.

We claim:

1. A heating apparatus comprising a generator for a mixed iiuid heating medium consisting of products of combustion and steam, said generator comprising a burner and a valve for controlling the supply of fuel to the burner, a radiating system comprising a plurality of separate radiators, an exhausting mechanism connected with all of the radiators for withdrawing gaseous products therefrom and creating a subatmospheric pressure therein and in the generator, conduits for the heating medium leading from the generator to the radiators, and thermostatic means for controlling the valve so as to decrease the fuel supply to the burner when the temperature of the gases exhausted from the radiating system exceeds a predetermined maximum.

2. A heating apparatus comprising a generator for a mixed fluid heating medium consisting \of products of combustion and steam, a radiating system comprising a plurality of separate radiators, an exhausting mechanism connected with al1 of the radiators for withdrawing gaseous products therefrom and creating a subatmospheric pressure therein and in the genera.- tor, conduits for the heating medium leading from the generator to the radiators, and thermostatic means for decreasing the ow of fuel to the generator when the temperature of the gases withdrawn from the radiating system exceeds a predetermined maximum, and for again increasing the flow of fuelwhen the temperature of the gases falls below this maximum.

3. A heating apparatus comprising a generator for a mixed id heating medium consisting of products of combustion and steam, a radiating system comprising a plurality of separate radiators, conduits for the heating medium leading from the generator to the radiators, an exhausting mechanism connected with the radiating system for withdrawing non-condensible gases therefrom and lowering the pressure therein and in the generator, manually operated means for remote control of the generator, and thermostatically controlled means for automatically decreasing the flow of the fuel to the generator when the temperature of the gases withdrawn from the radiating system exceeds to a predetermined maximum.

4. A heating apparatus comprising a generator for a mixed fluid heating medium consisting of products of combustionand steam, a radiating system comprising a plurality of separate radiators, conduits for the heating medium leading from the generator to the radiators, an exhausting mechanism connected with the radiating system for withdrawing non-condensible gases therefrom and lowering the .pressure therein and in the generator, and manu'- ally operated means for simultaneous remote control of the generator and exhausting mechanism by successive actuations, one adjustment of said manually operating means functioning to cause the exhausting means to remain in action after the generator burners have ceased to function.

5. A heating apparatus comprising a generator for a mixed fluid heating medium consisting of products of combustion and steam, said generator comprising a burner and a fuel supply pipe leading thereto, a radiating system comprising a plurality of radiators, an exhausting mechanism connected with the radiators for -with- Adrawing non-condensable gaseous products therefrom and creating a sub-atmospheric pressure therein and in the generator, conduits Ifor the heating medium leading from the generator to the radiators, means for returning condensate from the radiators to the generator, a valve in the fuel supply pipe and thermostatically controlled means for automatically opening or closing the valve as the temperature of the gases exhausted fromthe system fall below or rise above respectively a predetermined temperature.

6. A heating apparatus comprising a generator for a .mixed uid heating medium consisting of products of combustion and steam, said generator comprising a burner and a fuel supply pipe leading thereto, a radiating system comprising a plurality of radiators, an exhausting mechanism connected with the radiators for withdrawing non-condensable gaseous products therefrom and creating a sub-atmospheric pressure therein and in the generator, conduits for the heating medium leading from the generator to the radiators, means for returning condensate from the radiators to the generator, a valve in the fuel'supply pipe, and thermostatically controlled means for automatically opening or closing the valve in response to variations below or above a predetermined temperature respectively in a space heated by the apparatus or when the temperature of the gases exhausted from the system respectively fall below or rise above a predetermined temperature.

'7. A heating apparatus comprising a generator for a mixed fluid heating medium consisting of products of combustion and steam, said generator comprising a burner and a fuel supply pipe leading thereto, a radiating system comprising a. plurality of radiators, an exhausting mechanism connected with the radiators for withdrawing non-condensable gaseous,` products i therefrom and creating a sub-atmospheric pressure therein and in the generator, conduits for the heating medium leading from the generator to the radiators, means for returning condensate from the radiators to the generator, a pair of valves in the supply pipe, the fiow of fuel to the burner being cut oif when either valve is closed, manually operable means for remote control of the first valve and the exhausting mechanism, and thermostatically controlled means for automatically opening or closing the second valve as the temperaturey of the gases exhausted from the system respectively fall below or rise above a predetermined temperature.

8. A heating apparatus comprising a generator for a mixed fluidheating medium consisting of products of combustion and steam, said generatorcomprising a burner and a fuel supply pipe leading thereto, a radiating system comprising a plurality of radiators, an exhausting mechanism connected with the radiators for withdrawing non-condensable gaseous products therefrom and creating a sub-atmospheric pressure therein and in the generator, conduits for the heating medium leading fromthe generator to the radiators, means for returning condensate from the radiators to the generator, a pair of valves in the supply pipe, the flow of fuel to the burner being cut off when either valve is closed, manually operable means for remote control of the first valve and the exhausting mechanism, and thermostatically controlled means for automatically opening or closing the second valve in response to variations below or above a predetermined temperature in a space heated by the apparatus, or when the temperature of the gases exhausted from the system fall respectively below or rise above a certain predetermined temperature.

CLAYTON A. DUNHAM. AUBRA R. DUNHAM. 

